Improving high-power properties of PZT ceramics by external DC bias field

This paper concludes that the deterioration of the mechanical quality factor Q_m when operated under high power, can be recovered by externally applying positive DC bias field. Material constants for piezoelectric ceramics are generally characterized under low-power conditions. However, high-power properties deviate significantly from the ones measured under low-power conditions (Q_m degrades by a factor of ~2). DC Bias field helps to recover the properties of the ceramic under high-power conditions. The DC bias field of 200 V/mm exhibits an almost equivalent “opposite” change rate to the vibration velocity of 0.1 m/s. It is also notable that the piezoelectric loss tan θ’ can be decreased most effectively under positive DC bias field (1.9% per 100 V/mm for the hard PZT and 3.1% per 100 V/mm for the soft PZT), in comparison with the elastic or dielectric losses. This report presents a comprehensive analysis on the low- and high-power piezoelectric properties of hard and soft Lead Zirconate Titanates (PZT's) under externally applied DC bias field in the k₃₁ resonance mode (transverse extensional).